function subfrom() {
    var from = document.getElementById("i")
    console.log(from.value);

    var j = document.getElementById("j")
    var k = document.getElementById("k")

    if (!(j.checked || k.checked)) {
        j.checked = true;
    } else {
        [j.checked, k.checked] = [k.checked, j.checked]
    }

}